Mold for continuous centrifugal casting

ABSTRACT

Mold for continuous centrifugal casting comprises a rotary inner part in contact with the metal being cast and a stationary outer part through which cooling liquid is supplied, the two parts being connected by rotary seals of the labyrinth type.

ited States Peytavin et a1.

June 5, 1973 MOLD FOR CONTINUOUS CENTRIFUGAL CASTING Inventors: PierrePeytavin, Neuilly-sur-Seine; Louis Babel, Sauvigny-les- Bois, both ofFrance Assignee: Societe Civile DEtudes DeCentrifugation, Paris, FranceFiled: Dec. 28, 1971 Appl. No.: 212,997

Foreign Application Priority Data Dec. 30, 1970 France .7047337 US. Cl...164/283, 164/84, 164/297 Int. Cl. ..B22d 11/06, B22d 13/02 Field ofSearch ..164/84, 89, 273,

[56] References Cited UNITED STATES PATENTS 3,022,552 2/1962 Tessman..164/283 X 3,487,876 1/1970 Bucci ..l64/84 X 3,651,859 3/1972 Wahl eta1. ..164/297 X FOREIGN PATENTS OR APPLICATIONS 721,696 l/l955 GreatBritain 164/297 Primary ExaminerJ. Spencer Overholser AssistantExaminer-John E. Roethel Attorney-Joseph F. Bris'ebois and John A.Feketis [57] ABSTRACT Mold for continuous centrifugal casting comprisesa rotary inner part in contact with the metal being cast and astationary outer part through which cooling liquid is supplied, the twoparts being connected by rotary seals of the labyrinth type.

19 Claims, 2 Drawing Figures Patented June 5, 1973 3,736,980

2 Sheets-g 1 Patentgcl June 5, 1973 3,736,980

eeeeeeeeeeee t2 MOLD FOR CONTINUOUS CENTRIFUGAL CASTING SUMMARY OF THEINVENTION This invention relates to a mold for use in the continuousrotary vertical casting of steel castings.

The molds used in known processes of continuous casting are generallycooled by circulating water therethrough and comprise, for this purpose,a hollow annular or tubular space, the internal wall of which is thecooling wall of the mold proper.

In order to permit this circulation of water the rotary molds in presentuse comprise rotary seals which ensure fluid tightness between themobile rotary part of the seal and the fixed support for the moldthrough which the cooling water is supplied and withdrawn.

In view of the relatively large flow of water required to cool the mold,these seals must be constructed to ensure adequate sealing at relativelyhigh pressures and are thus subject to considerable wear during rotationof the mold.

It follows that it is not possible to turn the molds at high speeds inactual practice because the sealing means are not capable of toleratingsuch rotary speeds. However, the lower speeds used are neverthelesssufficient to cause relatively rapid deterioration of the seals, whichmust then be replaced.

The invention therefore proposes that a rotary mold be provided which iscooled by the circulation of a fluid, normally water, and which iscapable of turning at very high speeds while engendering relativelylittle friction. Moreover, the mold according to the invention does notrequire frequent changing of the seals and is thus much more economicalto operate than the molds heretofore known.

It is an object of the present invention to provide a mold forcontinuous vertical rotary casting which is cooled externally by thecirculation of a cooling fluid and comprises a rotary part constitutingthe mold proper and having a cooling wall, together with a stationarycoaxial part for supplying fluid and directing this fluid against thecooling wall, characterized by the fact that the rotating and stationaryparts define at least one annular labyrinth to force said fluid, or atleast the greater part thereof, to flow along the cooling wall.

As a consequence of the invention it is possible to have only very smallleakage at the level of the stationary member through which the fluid issupplied, even though the device comprises one or more distributionchambers having a substantial volume and the fluid is under highpressure in order to ensure a regular flow the full length of thecooling wall.

In a preferred embodiment of the invention the stationary part throughwhich the fluid is supplied is concentric with the rotating part and ispositioned, for example, around the upper part thereof. In this case,the labyrinth is preferably formed, on the one hand, by the uppersubstantially horizontal surface of the stationary part for supplyingfluid and by the upper flange of the rotating part which is positionedfacing this upper surface. Thus, the fluid, water for example, directedagainst the cooling wall of the rotating part of the mold, cannot escapethrough this upper labyrinth, except for minor leakage, and is thus ledto descend the length of the cooling wall of the rotating part of themold until the bottom of this wall, from whence it is exhausted. In suchan embodiment, it may be advantageous, in order to obtain a particularlycompact and well-guided mold, to position the bearings directlysupporting the mold around the rotating part of the mold, and thusdirectly above or below the stationary member for supplying water to themold. In this case, in accordance with the invention, the rotating partof the mold comprises, on the one hand, a concentric portion positioned,with a certain clearance, around the cooling wall of the mold, so as todefine with this wall an annular canal and, on the other hand, a flangefixed to said rotating portion and extending between the stationarysupply means and the stationary part of the bearings, or journals, saidflange defining, with the opposite surface of the stationary supplypart, a labyrinth to prevent the passage of water, except for minorleakage.

In such an embodiment, the device for supplying liquid may, for example,consist of a stationary ring defining a single chamber for holding fluidunder pressure and having one or more openings in its inner part in thevicinity of the external cooling wall of the mold. The upper and lowerwalls of this ring form, with the corresponding flanges of the rotatingpart, labyrinths preventing the escape of the water from either side ofthe ring. The outer part of the ring has one or more radial supply ductspositioned, for example, in the vanes connecting said ring to aconcentric outer support, and the spaces between said vanes permit thepassage and descent of cooling water from leakages through the upperlabyrinth.

The discharge of the fluid or the cooling water may be into the openair, or through a duct, for example, a toroid in form, similar to thestationary supply means, in which case one or more sealing labyrinthsmay also be provided at the level of discharge.

When the rotating part of the mold has an external portion which isconcentric with the cooling wall and defines therewith an annular duct,it is possible to position at the bottom of this portion one or moreradial outlets opening, on the one hand, into the open air and, on theother hand, into the lower part of said annular cooling duct.

' When, in accordance with a variation of the invention, the support forthe mold is not positioned directly around the part in contact with theliquid metal of the mold, it is possible to eliminate the concentricportion, with the annular cooling duct being then defined, on the onehand, by the external wall of the rotating part of the mold and, on theother hand, by a stationary wall of the means for supplying coolingfluid opposite said external wall. In accordance with a preferredembodiment of the invention, the teeth of the sealing laby rinths arevertically positioned. The play between the teeth may be, for example,of the order of 0.5 mm in a vertical direction and 1.5 mm in a radialdirection, allowing for the fact that the greatest expansion due to theheat caused by the casting takes place radially. Experience has shownthat, with such clearances, for the rate of flow utilized, the totalleakage of water may be limited to about 15 percent.

The invention is particularly adapted to the rotary casting of solidcylindrical castings in which the speed of rotation of the mold isgenerally between 30 and r.p.m.

Other advantages and characteristics of the invention will appear from areading of the following description of a preferred embodiment of theinvention, given purely by way of illustration, with reference to theaccompanying drawings, in which:

FIG. I is an axial sectional view according to the invention; and

FIG. 2 is a schematic perspective view of the stationary supply portionof said mold.

The mold illustrated and described below is adapted for use in a processof continuous rotary vertical casting but, of course, the invention isequally applicable to a continuous rotary casting process utilizing anonvertical axis.

The mold illustrated comprises a movable part I rotating about avertical axis 2. The mold per se consists of a cylindrical or slightlyfrusto-conical portion 3 made of copper or like metal, the internal wall4 of which is directly in contact with liquid metal while the steel isbeing continuously being poured.

This portion 3 has an external surface 5 forming the cooling surface indirect contact with the circulation of cooling water. At its upper endthe rotary copper member 3 is attached to a horizontal flange 6 which issurmounted by an annular removable protective member 7 adapted toprotect the upper surface of the flange 6 from contact with splatters ofliquid or incandescent taken through a mold particles. Beneath the innersurface of this horizontal flanges 6 is the stationary water-supplyingpart of the mold consisting principally of a toroid 8 which isrectangular in section, and the hollow interior of which encircles theupper part of the external cooling wall 5. This toroid defines a singleannular chamber holding a substantial volume of water under pressure inorder to ensure a regular flow of water along the length of the wall 5.As may be seen in greater detail on FIG. 2, the toroid 8 is attached byvanes It) to a cylindrical member 11, which is itself attached by aflange to a support 12. The cooling water is introduced into the toroid8 through an outer duct, not shown, opening into an oritice 13 in themember 1B. This orifice leads to a duct inside the vane in alignmentwith the orifice 13, said vane 10 having, for example, a width greaterthan that of the other vanes M in order to accommodate the duct leadingthe water to the interior of the toroid 8. Of course, it is alsopossible to bring the water into the totold through several vanes suchas lltl.

In accordance with the invention, the upper surface of the toroid 8 isprovided with a certain number of circular teeth which form a sealinglabyrinth 14 with the corresponding teeth on the lower surface of therotating flange 6, in order to require almost all the cooling water torun the length of the cooling wall 5 toward the bottom. Taking intoaccount, however, the high pressure of the liquid in the toroid 8, asmall part of the cooling water leaks along the labyrinth I4 and,circulating between the flange 6 and the upper part of the toroid 8,reaches the periphery of the toroid. At this point, the leakage waterdescends between the vanes 10 to be discharged in the direction of thearrows shown in the drawing.

As seen on FIG. I, the toroid 8 may advantageously comprise aradioactive source 115 in the form of a tube passing through aprotective cylinder 16, of lead for example, or of any other suitablematerial, said cylinder having, on the side of the axis 2, a radialsection of material 17 which is permeable to radiation in order topermit the source to supply radiation toward the axis of rotation 2 ofthe mold.

A radiation-sensitive device, not shown, diametrically opposite thesource 15, and preferably outside the mold, receives the radiation ofthe source, and is adapted to controlthe level of the rnetal'inside themold 3.

In accordance with a particularly valuable embodiment of the invention,the rotating part 1 of the mold is supported by stationary bearing meanscarried by arms 19 similar to the vanes 10, on the support 12, saidbearing means 18 being positioned concentrically of the mold 1 below thesupply toroid 8. In this case, as in the embodiment previouslydescribed, the external cooling wall 5 extends almost the full height ofthe mold 3, and is attached to a concentric portion 19 which extends,for reasons of strength, to the upper part of the mold. Orifices 20 arethen provided in this portion 19 opposite the chamber 9 in the toroid 8to permit the passage of water to the cooling wall 5. This portion 19 isspaced from wall 5 to form an annular duct 2H extending almost the fullheight of the mold so that the portion 19 is itself at a very lowtemperature which is no greater than the temperature of the coolingwater. The portion 19 has an internal bearing race 22 opposite a race 23carried by the support 18.

In order to prevent the cooling water from reaching the bearings 25, theportion 19 has, according to one embodiment of the invention, anintermediate flange 26, extending between the toroid 8 and the support18. In accordance with the invention, this flange 26 has a certainnumber of circular teeth cooperating with circular teeth on the lowersurface of the lower wall 27 of the toroid 8 to form a sealing labyrinth28. The leakages which occur pass outwardly along the upper sur face ofthe flange 26 and fall along an inclined edge of the flange 26 betweenthe arms 19 to rejoin the water from the leakages of the labyrinth 14.

in a preferred embodiment of the invention the labyrinths such as 14 and28 have a vertical clearance between their teeth which is less than theradial clearance between these teeth, since the expansion of the rotarypart of the mold is greater than the vertical expansion of the mold. Fora mold according to the invention having an interior wall 3 made ofcopper and a diameter of the order of to mm, the vertical clearancebetween the tops of the teeth and the bottoms of the groovestherebetween is of the order of 0.5 mm, whereas the radial clearancebetween the opposed sides of the teeth is of the order of 1.5 mm.

In the mold illustrated in the drawings the cooling water is removedthrough the lower part of the mold. For this purpose the lower part ofthe portion 19 has a substantially horizontal flange 29 provided with acertain number of radial passages 30 opening into the lower part of theannular duct 21. These passages 30 then open into an annular inclinedduct 31 formed by the deflectors 32 and 33 positioned at the end of thehorizontal flange 29. From this point the cooling water passes outthrough a vertical annular discharge duct 34 positioned between the arms19, the discharged water being then rejoined by the leakage water fromthe labyrinths M and 28.

The mold according to the invention may be mounted to rotate freely, in.which case it is driven in rotation by the solid part of the castingbeing poured, which is itself driven in rotation in a known manner bythe extractors, or the mold itself may be directly driven. In this caseit comprises, for example, a toothed ring 35 engaging a gear wheel 36 ondriving means shown in phantom lines on the drawings. in this case, atubular inclined passage is provided in place of the arm 19 at thisposition in order to permit access by the pinion 36 to this tubularmember, while protecting it from the leakage and discharge water.

The bearings 25 and/or the ring 35 may advantageously be lubricated by afilm of oil, which film is introduced through one or more radialorifices, not shown, passing through the support 18. A labyrinth member36 may be provided between the lower part of the deflector 33 whichrotates and the lower part of the support 18 in order to prevent theescape of lubricating oil in the outlet water.

The invention as shown on the drawing is, of course, subject tomodification in many ways. Thus the stationary means for supplying watersuch as the toroid 8 may be positioned midway of the height of the moldor at its bottom instead of at the top of the mold, in which case awater outlet may also be provided at the upper part of the mold. It isalso possible to position the water supply means coaxially above orbelow the rotary mold, with the water then leaving the device not in aradial direction but in a more or less axial direction. The teeth of thelabyrinth may, in this case, be horizontal, instead of being vertical asin the drawing. On the other hand, the rotary part of the mold may besupported by means positioned above or below the part 3 in contact withthe metal, and which may be cooled. In this case the intermediateflanges such as 26 may be unnecessary and it is also possible toeliminate the portion 19 which may then be replaced by a wall concentricwith the wall 5 and attached to the supply means such as 8. However, itwill be seen that the invention makes it possible, as in the case of theembodiment described, to provide in a compact manner, concentricallywith cooling wall 5, both a support for the mold, a driving ring, and afixed supply means, all while guaranteeing the water tightness of thebearings and teeth, and permitting the radioactive source forcontrolling the molten metal level to be judiciously positioned.

While one particular embodiment of the invention has been described, itis obvious that the scope of the invention is not limited to the detailsthereof and that it may be modified as to detail without therebydeparting from the basic principles of the invention'as defined by thefollowing claims:

What is claimed is:

1. In a mold for the continuous vertical rotary casting of metal, whichmold is externally cooled by the circulation of a cooling fluid, saidmold comprising a cylindrical rotary member mounted on bearings andconstituting the mold proper, said rotary member having an externalcooling surface, and stationary coaxial supply member for bringingliquid into contact with the cooling wall, the improvement comprising anannular labyrinth defined by interfitting teeth carried by said rotaryand stationary parts, which prevent the escape of the greater part ofsaid cooling fluid until it has travelled substantially the full lengthof the cooling wall.

2. Mold as claimed in claim 1 in which the stationary supply member ispositioned concentrically about said cooling surface and defines atleast one fluid distributing chamber.

3. Mold as claimed in claim 1 in which the rotary member comprises aportion extending coaxially of said outer supply member and at a certaindistance therefrom to define therebetween an annular cooling duct.

4. Mold as claimed in claim 3 which comprises at least one bearingpositioned concentrically of said coaxial portion, said bearing beingspaced from the fixed supply member by an intermediate flange carried bysaid rotating member and forming, with an opposite surface on said fixedsupply member, a sealing labyrinth.

5. Mold as claimed in claim 2 in which a surface of the stationarysupply member opposite the surface forming a labyrinth carries a secondflange fixed to the rotating part, with which itforms a second sealinglabyrinth.

6. Mold as claimed in claim 5 characterized by the fact that thestationary supply member is positioned above said bearing, with saidintermediate separating flange extending between these two members abouthalf way of the height of the mold.

7. Mold as claimed in claim 3 in which said coaxial portion extends forthe full height of the rotating part of the mold and has orifices nearthe outlet of the stationary supply member opening into said annularcooling duct.

8. Mold as claimed in claim 3 which comprises at its bottom a rotatingflange having at least one radial duct leading, on the one had, to thelower part of the annular cooling duct and on the other hand, tostationary discharge means.

9. Mold as claimed in claim 8 in which said radial ducts lead todeflectors defining one or more annular ducts opening into saidstationary discharge means.

10. Mold as claimed in claim I in which said fixed supply member forsupplying cooling liquid is a hollow toroid.

l1. Mold as claimed in claim It) in which said toroid is substantiallyrectangular in section with one of its lower and upper surfaces providedwith labyrinth teeth.

12. Mold as claimed in claim 11 in which the upper surface of the toroidhas a sealing labyrinth and in which said toroid is connected to astationary concentric support by a plurality of vanes definingtherebetween passages permitting the descent of water coming from leaksfrom the upper labyrinth.

l3. Mold as claimed in claim 4 in which said intermediate flangeterminates in a curved edge.

14. Mold as claimed in claim 10 which has at least one radioactivesource inside said torus.

15. Mold as claimed in claim 1 which comprises a driving ring gear.

16. Mold as claimed in claim 15 in which the ring gear is attached tothe exterior of one of the deflectors, the lower edge of said deflectorforming at least one sealing labyrinth with a corresponding surface onthe bearing of the mold.

l7. Mold as claimed in claim 1 in which, in the zone at which the liquidis discharged from the rotating member, said rotating part defines, withat least one of the surfaces of the discharge member, at least onesealing labyrinth.

l8. Mold as claimed in claim 1 comprising an annular protective elementattached to its upper part.

19. Mold as claimed in claim 4 comprising means for supplying saidbearing with a film of oil.

1. In a mold for the continuous vertical rotary casting of metal, whichmold is externally cooled by the circulation of a cooling fluid, saidmold comprising a cylindrical rotary member mounted on bearings andconstituting the mold proper, said rotary member having an externalcooling surface, and stationary coaxial supply member for bringingliquid into contact with the cooling wall, the improvement comprising anannular labyrinth defined by interfitting teeth carried by said rotaryand stationary parts, which prevent the escape of the greater part ofsaid cooling fluid until it has travelled substantially the full lengthof the cooling wall.
 2. Mold as claimed in claim 1 in which thestationary supply member is positioned concentrically about said coolingsurface and defines at least one fluid distributing chamber.
 3. Mold asclaimed in claim 1 in which the rotary member comprises a portionextending coaxially of said outer supply member and at a certaindistance therefrom to define therebetween an annular cooling duct. 4.Mold as claimed in claim 3 which comprises at least one bearingpositioned concentrically of said coaxial portion, said bearing beingspaced from the fixed supply member by an intermediate flange carried bysaid rotating member and forming, with an opposite surface on said fixedsupply member, a sealing labyrinth.
 5. Mold as claimed in claim 2 inwhich a surface of the stationary supply member opposite the surfaceforming a labyrinth carries a second flange fixed to the rotating part,with which it forms a second sealing labyrinth.
 6. Mold as claimed inclaim 5 characterized by the fact that the stationary supply member ispositioned above said bearing, with said intermediate separating flangeextending between these two members about half way of the height of themold.
 7. Mold as claimed in claim 3 in which said coaxial portionextends for the full height of the rotating part of the mold and hasorifices near the outlet of the stationary supply member opening intosaid annular cooling duct.
 8. Mold as claimed in claim 3 which comprisesat its bottom a rotating flange having at least one radial duct leading,on the one had, to the lower part of the annular cooling duct and on theother hand, to stationary discharge means.
 9. Mold as claimed in claim 8in which said radial ducts lead to deflectors defining one or moreannular ducts opening into said stationary discharge means.
 10. Mold asclaimed in claim 1 in which said fixed supply member for supplyingcooling liquid is a hollow toroid.
 11. Mold as claimed in claim 10 inwhich said toroid is substantially rectangular in section with one ofits lower and upper surfaces provided with labyrinth teeth.
 12. Mold asclaimed in claim 11 in which the upper surface of the toroid has asealing labyrinth and in which said toRoid is connected to a stationaryconcentric support by a plurality of vanes defining therebetweenpassages permitting the descent of water coming from leaks from theupper labyrinth.
 13. Mold as claimed in claim 4 in which saidintermediate flange terminates in a curved edge.
 14. Mold as claimed inclaim 10 which has at least one radioactive source inside said torus.15. Mold as claimed in claim 1 which comprises a driving ring gear. 16.Mold as claimed in claim 15 in which the ring gear is attached to theexterior of one of the deflectors, the lower edge of said deflectorforming at least one sealing labyrinth with a corresponding surface onthe bearing of the mold.
 17. Mold as claimed in claim 1 in which, in thezone at which the liquid is discharged from the rotating member, saidrotating part defines, with at least one of the surfaces of thedischarge member, at least one sealing labyrinth.
 18. Mold as claimed inclaim 1 comprising an annular protective element attached to its upperpart.
 19. Mold as claimed in claim 4 comprising means for supplying saidbearing with a film of oil.